Die Meistersinger von Nürnberg at the Bayreuth Festival in 1952, in what proved to be her only appearance at Bayreuth. In 1953, Della Casa sang Arabella in the Bavarian State Opera Company's performances at the London Royal Opera House, and sang the part of Octavian in Der Rosenkavalier for the first time, at the Salzburg Festival. On 20 November 1953, she made her debut at the Metropolitan Opera House in New York (the Met) as the Countess Almaviva in The Marriage of Figaro. Since her debut, she sang a total of 173 complete opera performances at the Met until her last performance there on 9 December 1967 as Countess Almaviva. Her repertoire at the Met was as follows: The Marriage of Figaro: Countess Almaviva (47 performances) Don Giovanni: Donna Elvira (34 performances) Die Meistersinger von Nürnberg: Eva (23 performances) Der Rosenkavalier: Die Feldmarschallin (17 performances) and Octavian (8 performances) Der Zigeunerbaron: Saffi (17 performances) Arabella: Arabella (16 performances) Ariadne auf Naxos: Ariadne (4 performances) Lohengrin: Elsa (4 performances) Madama Butterfly: Cio-Cio-San (2 performances) La bohème: Mimì (1 performance) In 1955, she sang the part of the Marschallin in Richard Strauss's Der Rosenkavalier for the first time; this was in a series of performances to celebrate the opening of the restored Vienna State Opera House. As a result, she had sung all three parts - the Marschallin, Octavian, Sophie - in Der Rosenkavalier as well as a single performance as Annina replacing an indisposed singer in Zurich. The Salzburg Festival was one of the most important venues in her career. She sang Ariadne in Strauss's Ariadne auf Naxos and Donna Elvira in Mozart's Don Giovanni in 1954, (once again) Donna Elvira in 1956, Chrysothemis in Strauss's Elektra and Countess Almaviva in 1957 (she also gave a recital at the Festival in the same year which has been preserved as a recording) and Arabella in 1958. Colleague Inge Borkh stated emphatically: "She was THE Arabella!" ("Sie war DIE Arabella!)" Della Casa sang Pamina in The Magic Flute in 1959. On 26 July 1960, the newly built Großes Festspielhaus in Salzburg opened with a performance of Der Rosenkavalier under Herbert von Karajan. She sang the part of the Marschallin in this performance with Sena Jurinac as Octavian and Hilde Güden as Sophie. Originally, Karajan and film director Paul Czinner planned to make a film of the performance and asked her to perform her